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1500 questions
6
votes
3 answers

Is "pitch diameter" the same as the distance between the centers?

I am designing gears in FreeCad, and printing then on a FlashForge Finder. I want to know if the pitch diameter is the same as the distance between the centers of the two gears. Both gears are external spur gears.
Avagadro's Number
6
votes
3 answers

Concrete formwork - best approach to counter uplift forces, for a freestanding pour?

I'm casting a 4m long triangular-profile reinforced gravity retaining wall against soil movement due to a 1 metre jump in ground level. The lateral forces and moments on the formwork have been easy to handle, but I'm trying to find a good approach…
Stilez
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Quaternion in control applications

In many application, the knowledge of the orientation of a body is essential for control purposes. There are several representations, where one is the Euler Angles and another is the Quaternion represenation, where the Euler Angles suffer from…
HansPeterLoft
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3 answers

For train track, why does the ballast need "good drainage"?

Why does the ballast of train track need good drainage? I read something about preventing "fouling" of the ballast, but don't know what that means or why it would be structurally bad. Could foundational support play a role, where soggy ground would…
DrZ214
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2 answers

What device is this, and how does it work?

There is this device I saw when I was a child at a big music store, that makes me curious. It was meant to listen some CDs to try them out before the purchase. You stand under a bell-shape kind of "speaker" to hear the music, but as soon as you step…
Zorgatone
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6
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7 answers

Do longer gun's barrel improve accuracy?

I have been reading a lot about guns in Wikipedia. I know much of the terminology of firearms. However, I was wondering why some firearms such as shotguns and rifles have very long barrels opposed to small handguns such as revolvers and pistols,…
Santropedro
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6
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4 answers

Why aren't screens round instead of rectangular?

Screens on TVs and phones et cetera are always rectangular. Why? Why are they not round? Eyes are round. The Sun, the source of almost all of our light, is round. Telescopes have round lenses and mirrors. If a photon has a shape it would be round…
LocalFluff
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2 answers

Is there a mechanism that can turn circular motion into alternating circular motion?

I'm trying to power and agitator (alternating circularly back and fourth) with a crank. I've seen a bunch of complicated mechanisms that do this, but I'm looking for the mechanically simplest method.
user379468
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6
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1 answer

How many states need to be measured for a reduced order observer?

I have a DC motor system with three states. The states are: $x_1$ = position (degrees), $x_2$ = velocity (degrees per second) $x_3$ = current (Amps). My plant input $u(t)$ is measured in volts. The dynamics are such…
Bret
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1 answer

How can I calculate the evaporation rate for a hazmat spill?

I was given formulas for general evaporation, for a spill calculator I am building. These are formulas, that are supposed to approximate evaporation, are for a number of different chemicals. Molecular weight is pulled from the chemical itself, same…
Duck
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2 answers

Is it safe to drop a bomb?

I realise that "bomb" can refer to all sorts explosives, but I am mainly interested in air-dropped bombs. Ever since reading about the USS Forrestal fire, I wondered about the safety of bombs when stored or transported in general- but in plain…
user7646
6
votes
3 answers

Mathematical representation of hinge and pin connection

Following on from this answer, I am reading about the difference between hinge and pin connections here, and I don't quite understand about it. I think I would need to see the mathematical representation ( the boundary condition) involving pin and…
Graviton
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2 answers

Why does compressed air energy storage use intercoolers?

Why do CAES systems have intercoolers after every compression stage? Isn't it a waste of work, since the air will cool anyway in the storage cavern?
Adnan Arif Sait
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6
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1 answer

Fragmentation of a curved cantilever beam under compression

Suppose we have a curved beam of a rectangular cross-section $A$, Young's modulus $E$, and a constant radius of curvature $R$. We now expose the beam to a vertical point load of magnitude $P$ at its free end: What I now want to know is where the…
David
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6
votes
4 answers

How to define Knurl on drawing?

I made this kind of knurl on shaft : but I am not sure how to be define on the drawing. I found some examples but not sure if they are correct. On the examples there type (GV) and depth of knurl and no more information. I will be very thankful if…
Stenly
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